Annular sealing rings, often referred to o-rings, are frequently utilized to provide a fluid seal between two members, such as two pipes, threaded or otherwise joined together. In the absence of a sealing ring, fluid within the pipes might leak through gaps at the joint at which the two members are connected.
Sealing rings are commercially available and are often made of a resilient, rubber-like material, for example rubber, ethylene, or propylene. Such materials are commercially available under the trademarks VITON and KALREZ. These scaling rings provide satisfactory sealing at comparatively low pressures and temperatures. However, at higher pressures and temperatures, for example pressures in excess of 3400 psia and temperatures in excess of 300.degree. F., these sealing rings do not always work satisfactorily. The high temperature might cause expansion of the members being joined, with resultant expansion of any gaps at the joint. The high temperature also might soften the material of the sealing ring. The high pressure then might result in extrusion of the sealing ring into the enlarged gaps. This can result in damage to the sealing ring. When the high pressure and high temperature condition ends, the members being joined contract, but any extruded portion of the scaling ring might not withdraw from the previously enlarged gap. In that event, the sealing ring may be damaged, and when the high pressure and high temperature condition is next experienced, the damaged sealing ring may not provide an adequate seal. This problem is exacerbated with each cycle of high pressure and high temperature.